[docbook] need coding for "Caps/smallcaps" and "bolditalic" text

Title: 

Hello,

Is there any coding/attribute 
available for making text SmallCaps (sc) and BoldItalic (both Bold as well as 
italic)?

I tried to use <emphasis 
role="smallcaps">...</emphasis> and <emphasis 
role="bolditalic">...</emphasis>. But it is not 
working.

NOTE: After this I tried 
<emphasis><emphasis 
role="bold">..blah...</emphasis></emphasis> for bold italic and 
it works. Is this nesting of <emphasis> 
acceptable?

Regards
Raju